Inductive charging with support for multiple charging protocols

ABSTRACT

A system and method for inductive charging with support for multiple charging protocols. In accordance with an embodiment, the system comprises a base unit having one or more charger coils, for use in inductive charging; and one or more components within the base unit and/or a mobile device for supporting multiple different charging protocols, for use with the mobile device. When a mobile device having one or more receiver coils or receivers associated with, is placed in proximity to the base unit, the system determines a charging protocol for use with the charger coil to inductively generate a current in the receiver coil or receiver associated with the mobile device, to charge or power the mobile device.

CLAIM OF PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/158,134, titled SYSTEM FOR WIRELESS POWER TRANSFER THAT SUPPORTSINTEROPERABILITY, AND MULTI-POLE MAGNETS FOR USE THEREWITH”, filed Jun.10, 2011; which application claims the benefit of priority to U.S.Provisional Patent Application No. 61/354,114, titled “IMPROVED MAGNETSFOR USE IN PROXIMITY TO MAGNETICALLY SENSITIVE PARTS OR DEVICES”,application No., filed Jun. 11, 2010; U.S. Provisional PatentApplication No. 61/387,895, titled “SYSTEM AND METHOD FOR PROVIDING AUNIVERSAL-COMPATIBLE WIRELESS POWER SYSTEM”, filed Sep. 29, 2010; andU.S. Provisional Patent Application No. 61/478,015, titled “SYSTEM ANDMETHOD FOR PROVIDING A UNIVERSAL-COMPATIBLE WIRELESS POWER SYSTEM”,filed Apr. 21, 2011; which application is related to U.S. patentapplication Ser. No. 11/669,113, titled “INDUCTIVE POWER SOURCE ANDCHARGING SYSTEM”, filed Jan. 30, 2007; U.S. patent application Ser. No.11/757,067, titled “POWER SOURCE, CHARGING SYSTEM, AND INDUCTIVERECEIVER FOR MOBILE DEVICES”, filed Jun. 1, 2007; U.S. patentapplication Ser. No. 12/116,876, titled “SYSTEM AND METHOD FOR INDUCTIVECHARGING OF PORTABLE DEVICES”, filed May 7, 2008; and U.S. patentapplication Ser. No. 12/769,586, titled “SYSTEM AND METHODS FORINDUCTIVE CHARGING, AND IMPROVEMENTS AND USES THEREOF”, filed Apr. 28,2010; each of which above applications are herein incorporated byreference.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

FIELD OF INVENTION

The invention is generally related to inductive charging, includingapplications for use in mobile or other devices and vehicles, andimproved compatibility and transfer of wireless power; and is alsorelated to the use of magnets in electronic devices, and in particularto devices or parts having proximity to magnetic sensors.

BACKGROUND

Wireless technologies for powering and charging mobile and otherelectronic devices and vehicles have been developed. These systemsgenerally use a wireless charger or transmitter system and a wirelessreceiver in combination to provide a means for transfer of power acrossa distance. For safe and efficient operation the two parts of the systemoften communicate with each other to verify the presence of receiversand/or initiate charging and continued power transfer. To enableinteroperability between chargers and receivers, it is important thatthe two parts of the system (the charger and the receiver) cancommunicate in a manner that allows such operation.

Additionally, many mobile, industrial, automotive, medical devices, etc.contain compasses or other components that are sensitive to magneticfield. At the same time, it is often desired to use magnets forfastening or attachment, or alignment purposes near such devices withoutaffecting the operation of such sensitive material. One application maybe fastening of a mobile device or phone to a surface in a car or othervehicle to avoid movement during transport.

These are the general areas that embodiments of the invention areintended to address.

SUMMARY

As described above, to enable interoperability between chargers andreceivers, it is important that the two parts of the system (the chargerand receiver) can communicate in a manner that allows operation. Withthe proliferation of different communication schemes, a multi-protocolsystem that can adapt and interoperate with different communicationprotocols allows maximum interoperability. Described herein are systemsand methods for providing such multi-protocol operation and maximuminteroperability. Also described herein are methods for use of magnetsin or around magnetically sensitive devices such that the operation ofsuch a device is not impaired. Applications in various devices andsystems are described. In particular, applications for fastening mobiledevices to their cases or other surfaces, and also alignment orattachment for power transfer or charging are described. Also describedherein are systems and methods for the use of multi-pole and othermagnets, in electronic and other articles, devices, components, or partsthereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates an example of a wireless charger or power system thatcomprises a charger or transmitter part, and a receiver part, inaccordance with an embodiment.

FIG. 2 shows a more detailed view of the wireless charger system with aresonant converter geometry, in accordance with an embodiment.

FIG. 3 illustrates a system wherein a dedicated RF channel foruni-directional or bi-directional communication between the charger andreceiver is implemented for validation and/or regulation purposes, inaccordance with an embodiment.

FIG. 4 illustrates the use a center-tapped receiver wherein during eachcycle current passes only through one part of the coil and one diode inthe receiver and therefore halves the rectification losses, inaccordance with an embodiment.

FIG. 5 illustrates that the charger and receiver coils can berepresented by their respective inductances by themselves and the mutualinductance between, in accordance with an embodiment.

FIG. 6 shows a wirelessly powered battery pack and receiver, inaccordance with an embodiment.

FIG. 7 illustrates the use of a battery cell connected through aprotection circuit comprising a battery protection IC that protects abattery from over-current and under or over voltage, in accordance withan embodiment.

FIG. 8 illustrates a typical charge cycle for a Lithium Ion battery, inaccordance with an embodiment.

FIG. 9 illustrates how the charger periodically activates the chargercoil driver and powers the charger coil with a drive signal ofappropriate frequency, in accordance with an embodiment.

FIG. 10 illustrates an example of the communication process andregulation of power and/or other functions, in accordance with anembodiment.

FIG. 11 shows a Notebook-style portfolio case and a mobile phone orcamera pouch, where magnets are used to secure a closing clasp or flap,in accordance with an embodiment.

FIG. 12 illustrates several commercially available mounts for devices,in accordance with an embodiment.

FIG. 13 shows an example of a power plug for an electronic device, inaccordance with an embodiment.

FIG. 14 shows an inductive wireless charger and/or power supply withmultiple charging stations, in accordance with an embodiment.

FIG. 15 illustrates several different placements and shapes for magnets,in accordance with an embodiment.

FIG. 16 shows a measured z-component along the axial direction ofmagnetization of a magnet, in accordance with an embodiment.

FIG. 17 illustrates the performance of a 50×50×1 mm³ magnet with one of10×10×1 mm³ dimension magnetized axially perpendicular to the squaresurface of the part, in accordance with an embodiment.

FIG. 18 illustrates how the same shape part can be periodically poled ina multi-pole pattern, in accordance with an embodiment.

FIG. 19 shows the drop off of maximum flux density value for a 10×10×1mm³ magnet magnetized periodically with a periodicity of 1 and 2 mm, inaccordance with an embodiment.

FIG. 20 shows several magnet types that are magnetized perpendicular tothe magnet surface (axially), in accordance with various embodiments.

FIG. 21 shows an example of various ring or arc multi-pole magnets, asmay be used to with a coil to provide alignment, in accordance with anembodiment.

FIG. 22 illustrates a ring magnet that includes a discontinuity, inaccordance with an embodiment.

FIG. 23 illustrates a multi-pole ring magnet with radially magnetizedsections, in accordance with an embodiment.

DETAILED DESCRIPTION

With the proliferation of electrical and electronic devices and vehicles(which are considered devices herein), simple and universal methods ofproviding power and or charging of these devices is becomingincreasingly important. To enable a user to easily charge or power thesedevices, a simple non-contact method such as wireless power transfer isincreasingly important.

Many of these devices contain internal batteries, and the device may ormay not be operating during receipt of power. Depending on the degree ofcharge status of the battery or its presence and the system design, theapplied power may provide power to the device, charge its battery or acombination of the above. The terms charging and/or power are usedinterchangeably herein to indicate that the received power can be usedfor either of these cases or a combination thereof. Unless specificallydescribed, these terms are therefore used interchangeably.

As shown in FIG. 1, a wireless charger or power system comprises acharger or transmitter part, and a receiver part. The charger ortransmitter can generate a repetitive power signal pattern (such as asinusoid or square wave from 10's of Hz to several MHz or even higherbut typically in the 100 kHz to several MHz range) with its coil drivecircuit and a coil or antenna for transmission of the power. The chargeror transmitter typically also includes a communication andregulation/control system that detects a receiver and/or turns theapplied power on or off and/or modify the amount of applied power bymechanisms such as changing the amplitude, frequency or duty cycle, etc.or a combination thereof of the applied power signal to the coil orantenna.

The second part of the system is a receiver that includes a coil orantenna to receive power, a method for change of the received AC voltageto DC voltage such as rectification and smoothing with one or morerectifiers or a bridge or synchronous rectifier, etc. and one or morecapacitors and optionally, a method for the receiver to communicate withthe charger.

In accordance with an embodiment, the method of communication betweenthe charger and receiver can be through the same coils as for transferof power, through a separate coil, through an RF or optical link orcombination thereof. In case of communication through the power transfercoil, one method for the communication is to modulate the load in thereceiver to affect the voltage in the receiver coil and therefore createa modulation in the charger coil parameters that can be detected throughmonitoring of its voltage or current. Other methods can includefrequency modulation by combining the received frequency with a localoscillator signal or inductive, capacitive, or resistive modulation ofthe output of the receiver coil.

In accordance with an embodiment, the communicated information can bethe output voltage, current, device or battery status, validation ID forreceiver, end of charge or various charge status information, receiverbattery, device, or coil temperature, or user data.

In accordance with an embodiment, the data communicated can be any ofthe information detailed herein, or the difference between these valuesand the desired value or simple commands to increase or decrease poweror simply one or more signals that would confirm presence of a receiveror a combination of the above. In addition, the receiver can includeother elements such as a dc to dc converter or regulator such as aswitching, buck, boost, buck/boost, or linear regulator. The receivermay also include a switch between the DC output of the receiver coil andits output to a device or battery or a device case or skin and in caseswhere the receiver is used to charge a battery, the receiver may alsoinclude a battery charger IC or circuitry and/or battery protectioncircuit and associated transistors, etc. The receiver and/or chargerand/or their coils can also include elements such as thermistors,magnetic shields or magnetic cores, magnetic sensors, and input voltagefilters, etc. for safety and/or emission compliance reasons. Inaddition, the charger and or receiver can include means to provide moreprecise alignment between the charger and receiver coils or antennas.These may include visual, physical, or magnetic means to assist the userin alignment of parts. To implement more positioning freedom of thereceiver on the charger, the size of the coils can also be mismatched.For example, the charger can comprise a larger coil size and thereceiver a smaller one or vice versa, so that the coils do not have tobe precisely aligned for power transfer.

In accordance with an embodiment, the power section (coil drive circuitand receiver power section) can be a resonant, zero switching, flyback,or any other appropriate topology. FIG. 2 shows a more detailed view ofthe wireless charger system with a resonant converter geometry where apair of transistors Q1 and Q2 (such as FETs) are driven by a half-bridgedriver IC and the voltage is applied to the coil L1 through one or morecapacitors shown as C1. The receiver includes a coil and an optionalcapacitor (for added efficiency) shown as C2 that may be in series or inparallel with the receiver coil L2. The charger and/or receiver coilsmay also include magnetic material layers behind them to increase theirinductance or to shield the magnetic field leakage to surrounding area.

In accordance with an embodiment, the charger also includes a circuitthat measures the current through and/or voltage across the charger coil(in this case a current sensor is shown in the figure as an example).Various demodulation methods for detection of the communication signalon the charger current or voltage are available. This demodulationmechanism can be an AM or FM receiver (depending on whether amplitude orfrequency modulation is employed in the receiver modulator) similar to aradio receiver tuned to the frequency of the communication or aheterodyne detector, etc.

In accordance with an embodiment, the microcontroller unit (MCU) in thecharger (MCU2) is responsible for understanding the communication signalfrom the detection/demodulation circuit and, depending on the algorithmused, making appropriate adjustments to the charger coil drive circuitryto achieve the desired output voltage, current or power from thereceiver output. In addition, MCU1 is responsible for processes such asperiodic start of the charger to seek a receiver at the start of charge,keeping the charger on when a receiver is found and accepted as a validreceiver, continuing to apply power and making necessary adjustments,and/or monitoring temperature or other environmental factors, providingaudio or visual indications to the user on the status of charging orpower process, etc. or terminating charging or application of power dueto end of charge or customer preference or over temperature, overcurrent, over voltage, or some other fault condition or to launch orstart another program or process. For example, the charger can be builtinto a car and once a valid receiver integrated into or on a mobiledevice, its case or skin, or battery is found, the charger may activatesome other functions such as Bluetooth connectivity to the device,displaying the device identity on a display, etc. Other similar actionscan be done in other environments. It may be useful in addition to thecommunication signal to detect the dc value of the current through thecharger coil. For example, faults may be caused by insertion or presenceof foreign objects such as metallic materials between the charger andreceiver. These materials may be heated by the application of the powerand can be detected through detection of the charger current ortemperature or comparison of input voltage, current, or power to thecharger and output voltage, current, or power from the receiver andconcluding that the ratio is out of normal range and extra power lossdue to unknown reasons is occurring. In these conditions or othersituations such as abnormal charger and/or receiver heating, the chargermay be programmed to declare a fault condition and shut down and/oralert the user or take other actions.

Once the charger MCU has received a signal and decoded this signal, itcan take action to provide more or less power to the charger coil. Thiscan be accomplished through known methods of adjusting the frequency,duty cycle or input voltage to the charger coil or a combination ofthese approaches. Depending on the system and the circuit used, the MCUcan directly adjust the bridge driver or an additional circuit such as afrequency oscillator may be necessary to drive the bridge driver or theFETs.

A typical circuit for the receiver in accordance with an embodiment, isalso shown in FIG. 2. In accordance with an embodiment, the receivercircuit can include a capacitor C2 in parallel or series with thereceiver coil to produce a tuned receiver circuit. This circuit is knownto increase the efficiency of a wireless power system. The rectified andsmoothed (through a bridge rectifier and capacitors) output of thereceiver coil and optional capacitor is either directly or through aswitch or regulator applied to the output. A microcontroller is used tomeasure various values such as output voltage, current, temperature,state of charge, battery full status, end of charge, etc. and to reportback to the charger to provide a closed loop system with the charger asdescribed above. In the circuit shown in FIG. 2, the receiver MCUcommunicates back to the charger by modulating the receiver load byrapidly closing and opening a switch in series with a modulation load ata pre-determined speed and coding pattern. This rapid load modulationtechnique at a frequency distinct from the power transfer frequency canbe easily detected by the charger. A capacitor and/or inductor can alsobe placed in parallel or in series with this load.

For example, one may assumes that the maximum current output of thereceiver is 1000 mA and the output voltage is 5 V for a maximum outputof 5 W. In this case, the minimum load resistance is 5 ohms. Amodulation load resistor of several ohms (20, or 10 ohms or smaller)would be able to provide a large modulation depth signal on the receivercoil voltage. Choosing a 5 ohm resistor would modulate the outputbetween a maximum current of 1 Amp or larger and a smaller value definedby the device load at the output. Such a large modulation can be easilydetected at the charger coil current or voltage as described above.

The receiver in FIG. 2 also shows an optional dc regulator that is usedto provide constant stable voltage to the receiver MCU. This voltagesupply may be necessary to avoid drop out of the receiver MCU duringstartup conditions where the power is varying largely or during changesin output current and also to enable the MCU to have a stable voltagereference source so it can measure the output voltage accurately.

In the above description, a uni-directional communication (from thereceiver to the charger) is described. However, this communication canalso be bi-directional and data can be transferred from the charger tothe receiver through modulation of the voltage or current in the chargercoil and read back by the microcontroller in the receiver detecting achange in the voltage or current, etc.

In accordance with an embodiment, in other geometries where positionindependence on placement of the receiver on the charger surface isachieved by having multiple charger coils in an array or pattern,similar drive and communication circuits in the charger and receiver canbe implemented. However, to detect the appropriate coil to activate inthe charger, the coils can be activated in a raster or zigzag fashion orother geometry and current drawn from a charger coil, strength ofvoltage, current, power or signal from the receiver or other methods canbe used to determine the closest match between position of one or moreof the charger coils and a receiver coil and the appropriate chargercoil or coils can be activated and modulated to provide optimum powertransfer to the receiver.

While a system for communication between the charger and receiverthrough the power transfer coil or antenna is described above, thecommunication can also be implemented through a separate coil, a radiofrequency link (am or fm or other communication method), an opticalcommunication system or a combination of the above. The communication inany of these methods can also be bi-directional rather thanuni-directional as described above. As an example, FIG. 3 shows a systemin accordance with an embodiment, wherein a dedicated RF channel foruni-directional or bi-directional communication between the charger andreceiver is implemented for validation and/or regulation purposes. Thissystem is similar to the system shown in FIG. 2, except rather than loadmodulation being the method of communication, the MCU in the receivertransmits the necessary information over an RF communication path. Asimilar system with LED or laser transceivers or detectors and lightsources can be implemented. Advantages of such system may be that thepower received is not modulated and therefore not wasted duringcommunication and/or that no noise due to the modulation is added to thesystem.

One of the disadvantages of the circuit shown in FIG. 2 is that in thereceiver circuit shown therein, the current path passes through 2 diodesand suffers 2 voltage drops resulting in large power dissipation andloss. For example, for Schottky diodes with forward voltage drop of 0.4V, at a current output of 1 A, each diode would lose 0.4 W of power fora combined power loss of 0.8 W for the two in a bridge rectifierconfiguration. For a 5 V, 1 A output power (5 W), this 0.8 W of powerloss presents a significant amount of loss (16%) just due to therectification system. In accordance with an embodiment, an alternativeis to use a center-tapped receiver as shown in FIG. 4 wherein duringeach cycle current passes only through one part of the coil and onediode in the receiver and therefore halves the rectification losses.Such a center tapped coil can be implemented in a wound wire geometrywith 2 sections of a wound wire or a printed circuit board coil or witha double or multi-sided sided PCB coil or a combination or even astamped, etched or otherwise manufactured coil or winding.

In any of the systems described above, as shown in FIG. 5, the chargerand receiver coils can be represented by their respective inductances bythemselves (L1 and L2) and the mutual inductance between them M which isdependent on the material between the 2 coils and their position withrespect to each other in x, y, and z dimensions. The couplingcoefficient between the coils k is given by:

k=M/(L1*L2)^(1/2)

The coupling coefficient is a measure of how closely the 2 coils arecoupled and may range from 0 (no coupling) to 1 (very tight coupling).In coils with small overlap, large gap between coils or dissimilar coils(in size, number of turns, coil winding or pattern overlap, etc.), thisvalue can be smaller than 1.

FIG. 6 shows a wirelessly powered battery pack and receiver inaccordance with an embodiment. The components of a typical commonbattery pack (battery cell and protection circuit, etc.) used in abattery device used in applications such as mobile phone, etc. are showninside the dashed lines. The components outside the dashed lines areadditional components necessary to enable safe wireless and wiredcharging of a battery pack. A battery pack may have four or moreexternal connector points that interface with a mobile device pins in abattery housing or with an external typical wired charger. In accordancewith an embodiment, the battery cell is connected as shown in FIG. 7 totwo of these connectors (shown in the figure as Batt+ and Batt−) througha protection circuit comprising a battery protection IC that protects abattery from over-current and under or over voltage. A typical IC may beSeiko 824 IC that uses 2 external FETs as shown in FIG. 7 to preventcurrent going from or to the battery cell (on the left) from theexternal battery pack connectors if a fault condition based on overcurrent, or battery cell over or under voltage is detected. Thisprovides safety during charging or discharging of the battery. Inaddition, a battery pack may include a PTC conductive polymer passivefuse. These devices can sense and shut off current by heating a layerinside the PTC if the amount of current passing exceeds a threshold. ThePTC device is reset once this current falls and the device cools.

In addition, in accordance with an embodiment, the battery pack cancontain a thermistor that the mobile device checks through one otherconnector on the battery pack to monitor the health of the pack, and insome embodiments an ID chip or microcontroller that the mobile deviceinterrogates through another connector to confirm an original batterymanufacturer or other information about the battery. Other connectorsand functions can be included in a battery pack to provide accuratebattery status and/or charging information to a device being powered bya battery pack or a charger charging the battery pack.

In addition to the components described above, In accordance with anembodiment, the receiver circuit comprises a receiver coil that could bea wound wire or PCB coil as described above, optional electromagneticshielding between the coil and the metal body of the battery, optionalalignment assisting parts such as magnets, etc., a receivercommunication circuit (such as the resistor and FET for load modulationshown in FIGS. 2 and 4), a wireless power receiver (such as rectifiersand capacitors as discussed above), and an optional Battery charger ICthat has a pre-programmed battery charging algorithm. Each type ofbattery and chemistry requires a pre-determined optimized profile forcharging of a battery. A typical charge cycle for a Lithium Ion (Li-Ion)is shown in FIG. 8. Such a battery may be charged up to a value of 4.2 Vat full capacity. The battery should be charged according to theguidelines of the manufacturer. For a battery of capacity C, the cellcan typically be charged at the rate 1C. In Stage 1, the maximumavailable current is applied and the cell voltage increases until thecell voltage reaches the final value (4.2 V). In that case, the chargerIC switches to Stage 2 where the charger IC switches to Constant Voltagecharging where the cell voltage does not change but current is drawnfrom the source to further fill up the battery. This second Stage maytake 1 or more hours and is necessary to fully charge the battery.Eventually, the battery will draw little (below a threshold) or nocurrent. At this stage, the battery is full and the charger maydiscontinue charging. The charger IC can periodically seek the conditionof the battery and top it off further if the battery has drained due tostand-by, etc.

Such multiple stages of battery charging may be implemented in firmwarewith the wireless power charger and receiver microcontrollers monitoringthe battery cell voltage, current, etc. and working in tandem and toprovide appropriate voltage, current, etc. for safe charging for anytype of battery. In another approach as shown in FIG. 6, a batterycharger IC chip that has specialized battery charging circuitry andalgorithm for a particular type of battery can be employed. Thesecharger ICs (with or without fuel gauge capability to accurately measurebattery status, etc.) are available for different battery chemistriesand are included in most mobile devices with mobile batteries such asmobile phones. They can include such safety features as a temperaturesensor, open circuit shut off, etc. and can provide other circuits ormicrocontrollers such useful information as end of charge signal,signaling for being in constant current or voltage (stage 1 or 2 above,etc.). In addition, some of these ICs allow the user to program and setthe maximum output current to the battery cell with an external resistoracross 2 pins of the IC.

In accordance with an embodiment, the wirelessly charged battery pack inaddition includes a micro-controller that coordinates and monitorsvarious points and may also include thermal sensors on the wirelesspower coil, battery cell and/or other points in the battery pack. Themicrocontroller also may communicate to the charger and can also monitorcommunication from the charger (in case of bi-directionalcommunication). Typical communication through load modulation isdescribed above.

Another aspect of a wirelessly charged battery pack is the optionalexternal/internal switch. A battery pack may receive power and becharged wirelessly or through the connectors of a battery pack. Forexample when such a battery pack is used in a mobile phone, the user maywish to place the phone on a wireless charger or plug the device in to awired charger for charging or charge the device as well as synchronizeor upload and/or download information. In the second case, it may beimportant for the battery pack to recognize current incoming to thebattery pack and to take some sort of action. This action may includenotifying the user, shutting off the wired charger by a switch or simplyshutting down the charger IC and sending a signal back through themicrocontroller and modulating the current back to the charger that awired charger is present (in case priority is to be given to the wiredcharger) or conversely to provide priority to the wireless charger andshut off wired charger access to battery when the wireless charger ischarging the battery. At either case, a protocol for dealing withpresence of two chargers simultaneously should be pre-established andimplemented in hardware and firmware.

As shown in FIG. 6, the wireless charging of battery occurs with currentflowing into the battery through the battery contacts from the mobiledevice. Typically, such current is provided by an external DC supply tothe mobile device (such as an AC/DC adaptor for a mobile phone) and theactual charging is handled by a charger IC chip or power management ICinside the mobile device that in addition to charging the battery,measures the battery's state of charge, health, verifies batteryauthenticity, and displays charge status through LEDs, display, etc. toa user. It may be therefore be advantageous to include a current sensecircuit at one of the battery pack contacts to measure and sense thedirection of current flow into or out of the battery. In case thecurrent is flowing in (i.e. battery being externally charged throughwired charging through a mobile device), the micro-controller may takethe actions described above and shut off wireless charging orconversely, provide priority to wireless charging and if it is present,not allow wired charging to occur as preferred by design.

In accordance with an embodiment, the firmware in the receivermicro-controller is a key element in the operation of this battery pack.The micro-controller can measure voltages and currents, flags, andtemperatures at appropriate locations for proper operation. Inaccordance with one embodiment, by way of example, the micro-controllercan measure the value of Vout from the rectifier circuit and attempt tokeep this constant throughout the charging cycle thereby providing astable regulated DC supply to the charger IC chip. The microcontrollercan send back the value of this voltage or error from a desired voltage(for example 5V) or simply a code for more or less power back to thecharger in a binary or multi-level coding scheme through a loadmodulation or other scheme (for example RF communication as describedearlier) back to the charger. The charger can then take action throughadjustment of input voltage to the charger coil, adjustment of thefrequency or duty cycle of the ac voltage applied to the charger coil tobring the Vout to within required voltage range. The micro-controllerthroughout the charging process, in addition, monitors the end of chargeand/or other signals from charger and/or protection circuit and thecurrent sense circuit (used to sense battery pack current direction andvalue) to take appropriate action. Li-ion batteries for example need tobe charged below a certain temperature for safety reasons. It istherefore essential to monitor the cell, wireless power receiver coil orother temperature and take appropriate action such as terminate chargingor lower charging current, etc. if a certain maximum temperature isexceeded.

It is important to realize that during charging, as shown in FIG. 8, thebattery cell voltage increases from 3 V or lower, to 4.2 V, as it ischarged. The V_(out) of the wireless power receiver is input to acharger IC and if this V_(out) is kept constant (for example 5V), alarge voltage drop (up to 2 V or more) can occur across this chipespecially during Stage 1 where maximum current is applied. Withcharging currents of up to 1 A, this may translate to up to 2 Watts ofwasted power/heat across this IC that may contribute to battery heating.It may be therefore preferable to implement a strategy whereby theV_(out) into the charger IC tracks the battery voltage thereby creatinga smaller voltage drop and therefore loss across the charger IC. Thiscan provide a significant improvement in performance since thermalperformance of the battery pack is very important.

The communication between the receiver and charger needs to follow apre-determined protocol, baud rate, modulation depth, etc. and apre-determined method for hand-shake, establishment of communication,and signaling, etc. as well as optionally methods for providing closedloop control and regulation of power, voltage, etc. in the receiver.

In accordance with an embodiment, a typical wireless power systemoperation can be as follows: As shown in FIG. 9, the chargerperiodically activates the charger coil driver and powers the chargercoil with a drive signal of appropriate frequency. During this ‘ping’process, if a receiver coil is placed on top or close to the chargercoil, power is received through the receiver coil and the receivercircuit is energized. The receiver microcontroller is activated by thereceived power and begins to perform an initiation process whereby thereceiver ID, its presence, power or voltage requirements, receiver orbattery temperature or state of charge and/or other information is sentback to the charger. If this information is verified and found to bevalid, then the charger proceeds to provide continuous power to thereceiver. The receiver may alternately send an end of charge,over-temperature, battery full, or other messages that will be handledappropriately by the charger and actions performed. The length of theping process should be planned to be of sufficient length for thereceiver to power up its microcontroller and to respond back and for theresponse to be received and understood. The length of time between thepings is determined by the designer. If ping process is performed often,the stand-by power use of the charger is higher. Alternately, if theping is done infrequently, the system will have a delay before thecharger discovers a receiver nearby.

Alternately, the ping operation can be initiated upon discovery of anearby receiver by other means. This provides a very low stand-by poweruse by the charger and may be performed by including a magnet in thereceiver and a magnet sensor in the charger or through optical,capacitive, weight or other methods for detection. Alternatively, thesystem can be designed to be always ON (i.e. the charger coil is poweredat an appropriate drive frequency) and presence of the receiver coilbrings the coil to resonance with the receiver coil and power transferoccurs. The receiver in this case may not even contain a microcontrollerand act autonomously and simply have a regulator to provide regulatedoutput power to a device, its kin or case, or battery.

In accordance with an embodiment, the protocol for communication can beany of, e.g. common RZ, NRZ, Manchester code, etc. used forcommunication. An example of the communication process and regulation ofpower and/or other functions is shown in FIG. 10. As discussed above,the charger may periodically start and apply a ping voltage ofpre-determined frequency and length to the charger coil (bottom figurein FIG. 10). The receiver is then activated and may begin to send backcommunication signals as shown in top of FIG. 10. The communicationsignal can include an optional preamble that is used to synchronize thedetection circuit in the charger and prepare it for detection ofcommunication. A communication containing a data packet may then follow,optionally followed by checksum and parity bits, etc. These processesare quite standard in communication systems and similar techniques canbe followed. The actual data packet can include information such as anID code for the receiver, received voltage, power, or current values,status of the battery, amount of power in the battery, battery orcircuit temperature, end of charge or battery full signals, presence ofexternal wired charger, or a number of the above. Also this packet mayinclude the actual voltage, power, current, etc. value or the differencebetween the actual value and the desired value or some encoded valuethat will be useful for the charger to determine how best to regulatethe output.

Alternatively, the communication signal can be a pre-determined patternthat is repetitive and simply lets the charger know that a receiver ispresent and/or that the receiver is a valid device within the powerrange of the charger, etc. Any combination of systems can be designed toprovide the required performance.

In response to the receiver providing information regarding output poweror voltage, etc. the charger may modify voltage, frequency, duty cycleof the charger coil signal or a combination of the above. The chargercan also use other techniques to modify the power out of the chargercoil and to adjust the received power. Alternatively the charger cansimply continue to provide power to the receiver if an approved receiveris detected and continues to be present. The charger may also monitorthe current into the charger coil and/or its temperature to ensure thatno extra-ordinary fault conditions exist. One example of this type offault may be if instead of a receiver, a metal object is placed on thecharger.

The charger can adjust a parameter to increase or decrease the power orvoltage in the receiver and then wait for the receiver to providefurther information before changing a parameter again or it can use moresophisticated Proportional Integral Derivative (PID) or other controlmechanisms for closing the loop with the receiver and achieving outputpower control. Alternatively, as described above, the charger canprovide a constant output power, and the receiver can regulate the powerthrough a regulator or a charger IC or a combination of these to providethe required power to a device or battery.

Various manufacturers may use different coding and also bit rates andprotocol. The control process used by different manufacturers may alsodiffer, further causing interoperability problems between variouschargers and receivers. A source of interoperability differences may bethe size, shape, and number of turns used for the power transfer coils.Furthermore, depending on the input voltage used, the design of awireless power system may step up or down the voltage in the receiverdepending on the voltage required by a device by having appropriatenumber of turns in the charger and receiver coils. However, a receiverfrom one manufacturer may then not be able to operate on anothermanufacturer charger due to these differences in designs employed. It istherefore extremely beneficial to provide a system that can operate withdifferent receivers or chargers and can be universal.

In accordance with an embodiment, to be able to detect and power/chargevarious receivers, the charger can be designed such that the initialPing signal is at such a frequency range to initially be able to powerand activate the receiver circuitry in any receiver during the pingprocess. After this initial power up of the receiver, the chargercommunication circuit should be able to detect and understand thecommunication signal from the receiver. Many microcontrollers are ableto communicate in multiple formats and may have different input pinsthat can be configured differently to simultaneously receive thecommunication signal and synchronize and understand the communication atdifferent baud rates and protocols. The charger firmware can then decideon what type of receiver is present and proceed to regulate or implementwhat is required (end of charge, shut-off, fault condition, etc.).Depending on the message received, then the charger can decide to changethe charger driver voltage amplitude, frequency, or duty cycle or acombination of these to provide the appropriate regulated output.

In accordance with an embodiment, the charger's behavior can also takeinto account the difference in the coil geometry, turns ratio, etc. Forexample, a charger and receiver pair from one or more manufacturers mayrequire operation of the charger drive voltage at 150 kHz. However, ifthe same receiver is placed on a charger from another manufacturer ordriven with different coil/input voltage combination, to achieve thesame output power, the charger frequency may need to be 200 kHz. Thecharger program may detect the type of receiver placed on it and shiftthe frequency appropriately to achieve a baseline output power andcontinue regulating from there.

As shown in FIG. 10, after the receiver sends back a communicationsignal back to the charger, in response to it, the charger adjusts itsfrequency and then awaits further information from the receiver. Thereceiver acknowledges the change and as shown in the second data packetin the receiver signal, has modified its state and communicates back tothe charger. This closed loop continues during the charging process.

For receivers that contain an onboard regulator for the output power,the input voltage to the regulator is not as critical since theregulator performs a smoothing function and keeps the output voltage atthe desired level with any load changes. It is however, important not toexceed the maximum rated input voltage of the regulator or to drop belowa level required so that the output voltage could no longer bemaintained at the required value. However, in general, inclusion of aregulator and/or a charger IC chip (for batteries) reduces thepower/voltage regulation requirements at the expense of the additionalsize and cost of this component.

While the system above describes a system where the communication isprimarily through the coil, as described earlier, communication may beimplemented through a separate coil, RF, optical system or a combinationof the above. In such circumstances, a multi-protocol system can also beused to interoperate between systems with different communication and/orcontrol protocols or even means of communication.

Alternately, the receiver may be designed to accommodate different typesof chargers. For example, once a receiver is awakened by a charger, itmay try to detect the ping frequency used by the charger. This may bedone by any number of phase locking or other techniques. Alternately,the receiver may send back a variety of trial communication signalsduring ping process to establish which type of device is performing theping. Once the type of the charger is established, the receiver canproceed and communicate with the appropriate communication protocol andfrequency with the charger.

The multi-protocol approach described above is important for developmentof a universal system that can operate amongst multiple systems andprovide user convenience.

The description for the systems above may use discreet electronicscomponents or some or all of the functions described above may beintegrated into an Application Specific Integrated Circuit (ASIC) toachieve smaller footprint, better performance/noise, etc. and/or costadvantages. Such integration is common in the Electronics industry andcan provide additional advantages here.

Magnets for Use with Magnetically Sensitive Devices and Materials

Magnetically sensitive devices, materials, or components are used in avariety of applications in industrial, consumer, credit, debit,Identification, or loyalty cards, computer, MP3 players, cameras,medical, satellite, marine, mining, transport, and militaryapplications. Examples of magnetically sensitive components or sensorsinclude traditional or electronic compasses, Hall sensors,magnetometers, disk drives, speakers, rotational or linear encoders,pneumatic sensors, electric motor position sensors, etc. These sensorsmonitor and/or measure slight amounts of magnetic field. For example, atraditional or electronic compass (consisting of magnetometer or HallEffect sensors) responds to the small magnetic field of the earth toprovide directional information to the user. Use of a magnet near such adevice would alter its performance and reliability. However, there areinstances where such a use would be beneficial. As an example, recently,there is interest in incorporation of electronic compasses in mobiledevices such as phones, GPS, cameras, electronic tablets, and electroniccompasses to provide the user a portable navigation capability.Simultaneously, these devices have often used magnets to secure thedevice in a holder, case, or holster or to attach the device to asurface such as a holder in a car. One example of use of magnets inmobile phones is in certain phones, such as Blackberry-type phones,where the presence of a device in its holster containing a small magnetis detected by a magnetic sensor in a phone and activates certainactions that may be selectable by the user on the phone. These actionscan for example consist of turning the ringer on the phone off orswitching to a vibrate mode.

In cases such as the phone described above, if a magnetic compass isimplemented in the phone, the presence of a magnet in a case caninterfere with the operation of the compass and/or navigationcapabilities of the device. Another example is the often used magneticdiscs or clasps in cases or holders for phones or cameras to close aprotective cover on a mobile device, phone, computer, GPS device, etc.In these and many other cases, it is desired to have an easy method offastening two parts together magnetically while not affecting theoperation of the device or system.

FIG. 11 shows a Notebook-style portfolio case (left) and a mobile phoneor camera pouch (right), where magnets are used to secure a closingclasp or flap. Magnets have also been used to secure cases or portfoliosto Notebook computers or the back of their screens. These devices oftenincorporate components such as disk drives or magnetically sensitivecomponents such as compasses, etc. that may be affected by use of suchmagnets. In addition, the existing magnetic sensors in the device (as inthe blackberry phone case discussed above) may be affected by suchmagnets.

In addition, in many instances, it is desirable to hold or mount variousdevices securely by use of magnets. These can include having aconvenient method for mounting of mobile phones, MP3 players, cameras,radar detectors, GPS units, compass, video screens, TVs, etc. in cars,boats, ships, trains, planes, helicopters, or other transport vehiclesor work or home areas. Several commercially available mounts for suchdevices are shown in FIG. 12. In these instances, a magnetic orferromagnetic base unit is coupled with a magnetic or ferromagneticmatching thin sticker or small sheet that can be attached or insertedinside a mobile device or its battery compartment or incorporated into askin or case for the device such that the device will be attracted tothe base and be held firmly during use or for storage. One or the otheror both the holder or the mount and the other part incorporated into oron a device can be magnetic, to provide the necessary attractive forcefor this operation. Similarly, if the device is sensitive to magneticfields, such a magnet can interfere with its operation.

Another area of use of magnets is in design of handbags, bags,backpacks, wallets, money clasps, etc. where magnets are used as aconvenient method of closing or fastening parts to close or shut partstogether. Use of magnets in such instances where the user may place amagnetically sensitive device, phone, camera, MP3 player with diskdrive, GPS unit, compass, or credit cards, etc. may cause problems. Inparticular, erasure of data in credit cards due to use of magnets inwallets or handbags can be a concern.

More recently, magnets have been used to provide easy and safeconnectivity between power or data cables and mobile devices or Notebookcomputers. As shown in FIG. 13 and described, for example in U.S. Pat.Nos. 7,311,526 and 7,645,143, a power plug for an electronic device orNotebook computer or deep fryer using a magnetic method for fasteningand attachment of the power cable and its plug to the matching connectorin the Notebook and a deep fryer. The magnet or ferromagnet material inthe part of the plug surrounding the 5 connectors shown is attracted tothe matching part in the Notebook and automatically aligns and connectsthe connectors in the 2 parts. The magnetic element on one or both ofthe plug and the device connector or receptacle can be a magnet toprovide the necessary attractive force. The advantages of this type ofconnector is that in case a user accidentally trips over such a cable,it would easily pull the cable out of the Notebook computer or deepfryer without damage to either side and pulling the product off to thefloor causing damage or injury. This is a considerable advantage overother types of connectors that are mated by force and insertion of onepart into another and liable to break in case of such accidents or causeunnecessary damage or injury. However, similar to the situationsdescribed above, use of such types of magnets near devices that aresensitive to the magnetic field such as mobile phones with compasses ordevices with magnetic sensors or hard drives near the connector isproblematic and therefore similar connectors are not used in manydevices that can take advantage of this technology.

Another area of use of magnets is in the area of wireless power. Withthe proliferation of mobile devices in recent years, the area ofpowering and charging these devices has attracted more attention. Thevast majority of the electronic devices in use today are powered and/orcharged through conduction of electricity through wires from a powersupply or charger to the device. While this method has proven to beefficient for most stationary devices, recently, there has been aninterest in providing wireless methods for powering or charging severalmobile devices, batteries, or electronics devices. The advantagesinclude the ability to eliminate a power/charger cord and thepossibility of implementing a universal charger/power supply that isable to charge/power multiple devices one at a time or simultaneously.In addition, in many situations, eliminating the connectors for chargingand/or power would improve device and/or battery reliability. The socalled “wireless power” methods can also be generally divided intoconductive and inductive methods. While the conductive methods use flowof current from a charger into the mobile devices and/or battery toprovide power and therefore are not strictly speaking wireless, theyoffer geometries where a user can place a device on a pad or similarobject and receive power through matching contacts on the back of adevice and the pad without ‘plugging in’ the device. The inductivemethods utilize coils or wires near the surface of a charger to create amagnetic field in the vicinity of the surface. A coil or wire in areceiver embedded into a device or battery that is in the vicinity ofthe surface can sense the magnetic field. Power from the charger can betransferred to the receiver without any wired connection through air orother media in between. The inductive method has several advantages overthe conductive approach, such as:

-   -   Connectors that are a major failure point in electronics are        eliminated.    -   Environmentally hermetic devices can be developed that are        immune to moisture or liquids.    -   The receiver can be built directly on the battery so the battery        can be charged through the outside shell of the device by        induction. This enables changing the battery of any existing        product after-market with a similar sized and shaped battery to        enable inductive charging.    -   With a properly designed charger pad, the charging is        independent of position and does not require placement of device        in any particular location or orientation.

Methods based on an array of connectors (e.g. U.S. Pat. No. 6,913,477B2) or strips of power (e.g. www.pureenergy.com) in a pad that can powermobile devices conductively have been proposed. Sakamoto (H. Sakamotoand K. Harada in PESC'93 Record, pp 168-174, Spain, (1992)) has alsoshown the possibility of recharging a device through a transformer coilwith a core where the sections of the transformer can be separated. S.Hui, et al., in Electronics Letters, 34, pp. 1052-1054, (1998) and S.Tang, et al., Electronics Letters, 36, pp 943-944 (2000), describe theuse of coreless printed circuit board transformers. Fernandez, et al.,in Proc. APECOZ, 2002, pp. 339-345, have described the process ofoptimization of PCB coils for power transfer. The use of a resonancecircuit is described in U.S. Publication No. 2009/0015075 and U.S.Publication No. 2009/0033564.

As described herein, powering or charging of a mobile or electronicdevice or battery can be used interchangeably. Many mobile devicesincorporate rechargeable batteries and require external DC power tocharge these batteries for operation. However, in case of some devicessuch as a notebook, computer, etc., while the device is connected to DCpower to charge its internal battery, the device can also be using theDC power to operate simultaneously. The ratio of power used for chargingthe internal rechargeable battery to operating the device depends on thedegree to which the battery is discharged, the power necessary tooperate the device, and what the device is doing at any given time. Inthe extreme, a laptop with its battery removed can only use the DC powerto operate. In this case no charging occurs and 100% of the provided DCpower is used to operate the device.

In some of the applications described above, magnets can be used toprovide alignment or a secure connection for an electrical contact. Forexample, in some implementations of the inductive charging technology,it may be desirable to provide alignment between the charger andreceiver coils by aligning them through use of disk, ring, or othermagnets attached to the two coils. When a receiver embedded in a device,battery, battery door, skin, or case is brought close to a chargersurface, the corresponding magnets can attract and bring the coils tothe necessary alignment for optimum power transfer. Several embodimentsfor implementing this, for example to provide higher insensitivity toplacement of the receiver, better mechanical and smaller volumerequirements, minimal impact on power transfer, etc., are described inU.S. patent applications “INDUCTIVE POWER SOURCE AND CHARGING SYSTEM”,application Ser. No. 11/669,113, filed Jan. 30, 2007 (subsequentlypublished as U.S. Publication No. 20070182367, and issued as U.S. Pat.No. 7,952,322); “POWER SOURCE, CHARGING SYSTEM, AND INDUCTIVE RECEIVERFOR MOBILE DEVICES”, application Ser. No. 11/757,067, filed Jun. 1, 2007(subsequently published as U.S. Publication No. 20070279002, and issuedas U.S. Pat. No. 7,948,208); “SYSTEM AND METHOD FOR INDUCTIVE CHARGINGOF PORTABLE DEVICES”, application Ser. No. 12/116,876, filed May 7, 2008(subsequently published as U.S. Publication No. 20090096413); and“SYSTEM AND METHODS FOR INDUCTIVE CHARGING, AND IMPROVEMENTS AND USESTHEREOF”; application Ser. No. 12/769,586, filed Apr. 28, 2010(subsequently published as U.S. Publication No. 20110050164), each ofwhich applications are hereby incorporated by reference herein.

FIG. 14 shows an Inductive wireless charger and/or power supply withmultiple charging stations in accordance with an embodiment. Theinductive receiver can be incorporated into a mobile device, its batterydoor, case or skin, a battery, etc. To align the coil in the charger andthe coil in the receiver, magnets that attract the coils into alignmentcan be incorporated or on around the coils. Many types of magnets suchas round discs, square, ring, oval, rectangular, arc, etc. can be usedfor alignment of coils. In FIG. 14, round disc (top) and ring (bottom)magnets are used for this alignment. One or many magnets can be used.Several different placements and shapes for magnets are shown in FIG. 15by way of example. For example, a single disc or square, or other shapedmagnet at the center of each coil can be used. In other implementations,4 disc or square magnets placed in the corners of a square pattern canbe used or other patterns. The patterns shown herein are shown by way ofexample. In accordance with other embodiments, other numbers and/orshapes of magnets or magnetization direction or strength can be used toachieve the desired alignment. It is possible to incorporate magnetswith attracting magnetic orientation in the two parts to be aligned oralternatively, only one or one set of magnets and a ferromagnetic ormagnetically attractable material used in the other part to achievesimilar alignment results.

The advantage of use of a single disc magnet in the center of a chargerand one in the center of a receiver is that the receiver can rotate withrespect to the charger and still maintain optimum alignment. With 4magnets placed as shown in FIG. 15, the coils can be rotated 90, 180, or270 degrees with respect to each other and still maintain alignment.Other shapes or number of magnets can be used and patterns in FIG. 15are shown only as a way of example. The magnets can be magnetized withthe magnet direction perpendicular to the face of the disk or magnet andby using magnet poles in the charger and receiver such that the pole isin the same direction in both, for example as south pole out of thepage. When the two devices are close to each other, the magnets attractand align the coils. U.S. patent applications “INDUCTIVE POWER SOURCEAND CHARGING SYSTEM”, application Ser. No. 11/669,113, filed Jan. 30,2007 (subsequently published as U.S. Publication No. 20070182367, andissued as U.S. Pat. No. 7,952,322); “POWER SOURCE, CHARGING SYSTEM, ANDINDUCTIVE RECEIVER FOR MOBILE DEVICES”, application Ser. No. 11/757,067,filed Jun. 1, 2007 (subsequently published as U.S. Publication No.20070279002, and issued as U.S. Pat. No. 7,948,208); “SYSTEM AND METHODFOR INDUCTIVE CHARGING OF PORTABLE DEVICES”, application Ser. No.12/116,876, filed May 7, 2008 (subsequently published as U.S.Publication No. 20090096413); and “SYSTEM AND METHODS FOR INDUCTIVECHARGING, AND IMPROVEMENTS AND USES THEREOF”; application Ser. No.12/769,586, filed Apr. 28, 2010 (subsequently published as U.S.Publication No. 20110050164), each of which applications are herebyincorporated by reference herein, each of which applications are herebyincorporated by reference herein, previously described improvements onthe design of alignment magnets. For example, in FIG. 15 or FIG. 16,disc, square, rectangular, or ring magnets are used in the charger andthe receiver with the magnets magnetized in the direction perpendicularto the flat surface. A gap in the ring magnet is incorporated to reducepotential eddy currents due to changing magnetic field of the wirelesscharger/power supply. Ring magnets have better performance for theseapplications due to the larger diameter of the magnet that can be usedin this case (thereby providing a larger alignment target for the user),the ability to rotate one coil with respect to the other one at anyangle and maintain alignment, and the ability to reduce or eliminate anypotential eddy currents through a cut in the ring as described above. Inaccordance with other embodiments, other shapes or combinations ofshapes, such as square, rectangle, circle, oval, or triangle, etc. rinsor other narrow wall, or others or combination of the above can be useddepending on the particular needs of the intended application.

In some situations, the charger/and or power supply is incorporated intoa mobile device or part that includes a magnetically sensitive portion.For example, the charger can be incorporated into a notebook or laptopor computer with a disk drive, compass, or other magnetically sensitiveparts. In these instances, incorporation of the magnet or magnets in thecharger as well as the receiver can pose problems for the deviceincorporating the charger as well as for the device or partincorporating the receiver.

In accordance with various embodiments, the coils described here can bemanufactured with wires, Litz wire, Printed circuit board (PCB),stamped, formed, shaped, etc. metal or magnetic material. The spiralpatterns shown here are for example only and the coils can be any shapeor size or pattern that could generate a magnetic field.

Similarly, the alignment can be achieved between a magnet or magnetsincorporated into or around one of the coils and a part constructed offerromagnetic or other magnetic material that can be attracted to themagnet for alignment. The magnet or the magnetically attracted part canbe made from Nickel, Iron, Cobalt, gadolinium and dysprosium, steel,etc. or an alloy of these materials or ceramic, Alnico, Ticonal, RareEarth magnets, flexible or injection molded or nano-crystalline magnetsso that the magnets on the receiver attract and attach to the magneticor ferromagnetic material on the other part. Examples of metal ormagnetic material or ferromagnetic material that could form the oppositeside are Nickel, Steel, cobalt, gadolinium and dysprosium, steel, etc.or an alloy of these material or ceramic, Alnico, Ticonal, Rare Earthmagnetic material, flexible or injection molded or nano-crystallinematerials or any other material that can be attracted to a magnet or analloy containing such. Of course, either the receiver or charger canincorporate a magnet and the other part a material that is attracted toa magnet or vice versa or both can contain magnets with poles arrangedsuch that they attract each other for alignment. The type of materialsdiscussed above or combination thereof can be used in any of thesecases. The magnets can be permanent magnets or electromagnets activatedby application of an electrical current.

Similarly, in conductive types of wireless or wire free charging orpower, the connectors on a receiver in or on a device or skin, etc. areoften magnetized to attract strips of metal or additional magnets on apad to make a strong connection. For example, some companies produce aconductive type of so called “wireless” or “wire-free” charger. In someinstances, connectors on the back of a mobile device incorporated intothe device, its skin, or battery door, or an additional part attached tothe back of the device contain a number of metallic contacts which makecontact with metal strips on a pad. The metal strips are connected to apower supply rail with an applied voltage and upon contact with thereceiver connectors and verification of the receiver, provide necessaryvoltage and/or current to the receiver. To enable a strong connectionbetween the receiver and the pad metal strips or to enable the receiverand the device it is attached or incorporated in, to be placed at anangle or vertically, etc., the metal strips are made of a magnetic orferromagnetic material such as Nickel, Iron, Cobalt, gadolinium anddysprosium, steel, etc. or an alloy so that the magnets on the receivercontact attract and attach to the strips. Enabling such an attractivecontact is especially important when it is desired that the device notmove during the charging process such as when the charger pad is used orincorporated into a car, airplane, ship, boat, etc. where motion ispresent. However, in instances where the mobile device contains acompass such as an electronic compass in certain phones, use of magnetsin the receiver connectors interferes with such an operation. Thereforethe manufacturer has generally not incorporated magnetic connectors forsuch instances, which eliminates the benefits of the magneticattachment.

In these and many other applications, it may be desirable to benefitfrom the seemingly contradictory use of magnets for their advantages inproviding an attractive force for fastening, mounting, holding, oralignment, while at the same time it is desired to minimize or eliminateany effect on magnetically sensitive components in the charger orreceiver or devices or parts nearby. This contradiction can be resolvedby realizing that it is possible to create magnets with a net magneticfield that is zero or small in areas near or far from the magnet and atthe same time that the part retains its magnetic or attractiveproperties at close distances and can provide attractive forces.

To achieve small overall net magnetic field, it is important to realizethat the magnetic field is a vector and fields from several magnets orparts or poles of the same magnet add to provide the total sum of thefield at any location in space.

Many magnets such as Rare Earth magnets are made using a sinteringprocess whereby the basic material components such as Iron, Nickel,Cobalt, and/or Rare Earth material are refined and then combined in thedesired composition and melted in a furnace to produce starting ingotsfor a magnet. The ingots are then ground and the resulting particles areplaced in a jig or mold with the desired shape and dimensions andpressed into shape while an external magnetic field is applied to orientthe particles. By applying the appropriate magnetic field in the desireddirection, in plane, out of plane, radial, or multi-pole poling of themagnet can be achieved. For example, multi-pole magnets are created bypulse magnetization. To create a linear period multi-pole magnet, amagnetizing fixture with a back and forth copper wire arrangement isused. Application of a short current pulse from a capacitor through thefixture produces a magnetic field strong enough to magnetize material inthe vicinity of the wire pattern. By controlling the shape and size ofthe induced magnetic field various magnet types can be created. Theresulting part is then treated in a sintering furnace to compact thematerial before further testing of the parameters and coating of thefinal magnet to avoid corrosion. As an example, multi-pole magnets withperiodicity of 1-2 mm in substrates of 2 mm thick or less have beenstudied for micro-actuator applications (J. Topfer, and V. Christoph,“Multi-pole Magnetization of NdFeB Sintered Magnets and Thick Films forMagnetic Micro-Actuators”, Sensors and Actuators, A 113 (2004) 257-263AND J. Töpfer, B. Pawlowski, H. Beer, K. Plötner, P. Hofmann, M.Herfurth, “Multi-pole magnetization of NdFeB magnets for magneticmicro-actuators and its characterization with a magnetic field mappingdevice, J. Magn. Magn. Mater. 270 (2004) 124-129).

Töpfer, et al. manufactured NdFeB square magnets of 50×50×1 mm³dimension magnetized axially perpendicular to the square surface of thepart and characterized it. FIG. 16 shows Measured z-component (along theaxial direction of magnetization) of the magnetic flux density of thismagnet measured by moving a Hall Sensor along the middle of one edge ofthe square to the opposite edge of the square 250 micrometers above thesurface of the magnet as shown in the inset. The results show that insuch a magnet, the field peaks at the edges and in the center, a strongdemagnetization field exists that almost reduces the magnetic flux tozero at this center, thereby not providing much attractive or retentionforce for such thin magnets.

In FIG. 17, the same researchers compare the performance of a 50×50×1mm³ magnet with one of 10×10×1 mm³ dimension magnetized axiallyperpendicular to the square surface of the part. The smaller magnetretains its magnetic flux to a greater degree at its center and hashigher peaks at the edges. Also note that the peak of the magnetic fluxis higher for this magnet.

To further retain high flux density in a magnet, the same shape part canbe periodically poled in a multi-pole pattern as shown in FIG. 18. Here,the 10×10×1 mm³ magnet is magnetized periodically with a periodicity of2 mm as shown on the top FIG. 18. The bottom figure shows the measuredmagnetic flux density. It can be seen that flux density follows thepoling pattern but in addition, comparing the magnitude of the fluxdensity, it can be seen that the peak values are about twice the peakvalue of the flux density in a uniformly magnetized magnet. In addition,the magnetic flux does not show any sign of demagnetization andreduction of the peak values at the center of the magnet that is seen inFIGS. 16 and 17. Overall, multi-pole magnetization can provide a methodfor achieving higher and more uniform magnetic flux in a magnet. Thesecharacteristics are desirable for applications described here whereretention and alignment of parts are required.

An important aspect of the performance of the multi-pole magnetsdescribed here is the performance of these magnets away from the surfaceof the magnets. FIG. 19 shows the drop off of maximum flux density valuefor a 10×10×1 mm³ magnet magnetized periodically with a periodicity of 1and 2 mm as shown on the top as a function of distance between the probeand the top of the magnet. It can be seen that the flux density dropsoff very quickly and reaches small values for over 1 mm. This is aresult of the geometry shown on the top of the figure. With multiplepoles present, as the distance between the probe and the magnetincreases, the probe measures the sum of the flux density from themultiple poles present and this value approaches zero quickly away fromthe surface. At the same time, near the surface, the flux density islarger for the multi-pole magnet as compared to a single pole magnet,and increases as the pole periodicity increases (up to a limit given thephysical dimensions of the magnet, its thickness, etc.). It is importantto recall that the peak for a uniformly magnetized magnet of samedimension was only around 0.13 T (<⅓ of the 1 mm periodically poledsimilarly sized magnet value) as shown in FIGS. 18 and 19. At the sametime, as discussed above, the uniformly magnetized magnet also showed avery significant reduction of the flux density at its center which isnot present for the multi-pole magnet.

In summary, the results above demonstrate that properly designedmulti-pole magnets can provide significantly higher and more uniformflux density near their surface while at the same time providing muchlower flux densities away from the surface.

These characteristics can be used to provide the combination ofcharacteristics that are useful for mounting, holding, attachment, andalignment purposes for the applications discussed earlier. By usingmulti-pole magnets higher retention and alignment force can be provided,while reducing the effect of any stray fields on nearby magneticallysensitive components, parts, or materials.

FIG. 20 shows several magnet types that are magnetized perpendicular tothe magnet surface (axially), in accordance with various embodiments.For example, FIG. 20 shows (a) rectangular magnet magnetized in acheckerboard pattern, (b) square magnet magnetized in a checkerboardpattern, (c) rectangular magnet magnetized in a single directionmulti-pole pattern, (d) square magnet magnetized in a single directionmulti-pole pattern, (e) disc magnet magnetized into 4 sections, (f) discmagnet magnetized into 8 sections, (g) ring magnet magnetized into 8sections, and (h) disc magnet magnetized into concentric circularsections. These patterns are shown by way of illustration and it isobvious that many types of magnets and shapes can be devised for variousapplications with regular or irregular shapes that have multi-polemagnetic patterns.

For applications in securing or mounting of parts to another part, amulti-pole magnet similar to magnets in FIG. 20 or another appropriateshape and size and number of poles can be devised for the device to bemounted or the mount and combined with a matching magnet or ferromagnetor other magnetically attractable material on the opposite part (deviceor mount) to provide attraction between the two parts. Since each magnetincludes a number of poles, this approach allows both for centralalignment between the two parts (i.e. their respective magnets ormagnetically attractable material are centered with respect to oneanother); and stepped or rotational alignment between the two parts(i.e. their respective magnets or magnetically attractable material canbe center-aligned with respect to one another, and then rotated aroundthose centers in steps corresponding to the number of poles, wherein ateach step the full magnetic attraction is provided). This allows fornovel uses of such magnets, for example to allow parts to be attached toone another in a variety or particular number of relative orientations.

In accordance with an embodiment, in applications such as shown in FIG.11-15, the appropriately designed magnet can be used instead of theuniformly magnetized magnets of earlier design, to provide stronger orsimilar attractive force while producing minimal or zero magnetic fieldaway from the magnet not to disturb other magnetically sensitive partsor devices.

As an example, in accordance with various embodiments, ring or arcmulti-pole magnets such as those shown in FIG. 21 can be used with thecoil to provide alignment. It will be evident that improvements such ascuts or discontinuities, etc. for reduction of eddy currents can beimplemented as in singly poled magnets described for example in U.S.patent applications “INDUCTIVE POWER SOURCE AND CHARGING SYSTEM”,application Ser. No. 11/669,113, filed Jan. 30, 2007 (subsequentlypublished as U.S. Publication No. 20070182367, and issued as U.S. Pat.No. 7,952,322); “POWER SOURCE, CHARGING SYSTEM, AND INDUCTIVE RECEIVERFOR MOBILE DEVICES”, application Ser. No. 11/757,067, filed Jun. 1, 2007(subsequently published as U.S. Publication No. 20070279002, and issuedas U.S. Pat. No. 7,948,208); “SYSTEM AND METHOD FOR INDUCTIVE CHARGINGOF PORTABLE DEVICES”, application Ser. No. 12/116,876, filed May 7, 2008(subsequently published as U.S. Publication No. 20090096413); and“SYSTEM AND METHODS FOR INDUCTIVE CHARGING, AND IMPROVEMENTS AND USESTHEREOF”; application Ser. No. 12/769,586, filed Apr. 28, 2010(subsequently published as U.S. Publication No. 20110050164), each ofwhich applications are hereby incorporated by reference herein. Forexample, the ring magnet in FIG. 22 shows an implementation of such adiscontinuity at the bottom of the figure.

While most of the description below is based on the inductive method ofpower transfer, the embodiments described here can be implemented witheither the inductive method or the conductive method or the magneticresonance method, optical, or other methods for power transfer some ofwhich have been described above. Inductive methods of power transfer aredescribed above as an example of the more general wireless powertransfer.

Furthermore, the type of magnets discussed above may be used withmagnetic shielding material commonly in use for reduction of AC or DCmagnetic field such as mumetal, etc. available from Magnetic ShieldCorporation or material such as thin flexible sheets available fromMaruwa or nano materials such as Finemet from Hitachi Corp orferromagnetic or alloys of ferromagnetic materials such as iron, nickeland cobalt. For example in the case of the inductive charger or receiverdescribed above, the area behind a coil can be covered by a magneticshield material and a square, rectangle, ring or arc of multi-polemagnet can be attached around and/or on such a shield and be used forattraction and alignment of the charger and receiver coil to each other.FIG. 22 shows such an arrangement where multi-pole magnets (multi-polering (left) and arc (right) magnet on or around an inductive coil) andmagnetic shielding material are used behind a coil. Here, the magneticshield layer or material shields behind the coil provides shielding fromthe alternating magnetic field of the coil. An optionalcut/discontinuity in the ring (shown at the bottom of the ring magnet onthe left) prevents or reduces eddy currents during operation of theinductive coil.

In addition, heat transfer layers can be incorporated to spread the heatgenerated. Such layers need to be designed not to interfere with theoperation of the coils. Since alternating magnetic fields are generatedand detected in an inductive system, use of a metal layer behind thecoil would produce eddy currents and loss. One method for providingthermal conductivity with metal layers is where a metal layer withdiscontinuous portions is placed behind and/or around the coil. In thiscase, the metal layer can comprise rectangular slices that can conductheat away from the center of a coil while, due to discontinuity betweenthe slices, the electrons can not flow in a circular motion due to thealternating magnetic field. The pattern described here has a number oftriangular slices but any other pattern which can provide heat transportbut does not allow carriers to circulate in a rotational pattern due tothe alternating magnetic field can be implemented.

Alternatively, multi-pole magnets can be manufactured by way of taking asingle poled magnet, cutting it into appropriate sections, andreassembling the pieces and attaching them together with an adhesive,glue, or other bonding agent or other material; or alternatively aholder, etc. or clamp or screws or external force or other methods, sothat the multi-pole geometry is achieved. For example, a single poledaxially poled (out of plane of ring) ring can be cut into 4, 8, 16, oranother number of even or odd sections, and half of the sections turnedover and reassembled to provide a multi-pole magnet. To aid in assemblyof such a magnet, it may be necessary to attach or place the parts on toanother solid continuous piece. This piece may be magnetic,ferromagnetic, or non-magnetic itself. For example, in the ring magnetexample above, the pieces of the ring magnet can be attached andreassembled in a multi-pole geometry on a stainless steel, iron, Nickel,plastic, or copper, etc. ring to aid in assembly and to hold thesections together. The properties of the backing material, itsthickness, etc. can also be optimized to provide necessary performance.For example, use of a ferromagnetic material as backing can furtherprovide a path for the magnetic flux in that section and provide furthertighter coupling between sections and reduction of magnetic field awayfrom the ring. It may also be desirable to sandwich the magnet on bothsides with similar or dissimilar backing material or layers, or usemultiple backing layers to further engineer symmetric or asymmetricproperties on the two sides of the multi-pole magnet.

FIG. 23 shows a multi-pole ring magnet with radially magnetizedsections. In use of the magnet for inductive charging applications, acut or break in the circle or arc magnets as described earlier can beused.

While in the above description, emphasis has been given to affixingelectronic parts, batteries, electric parts, etc to other parts orcomponents or cases, holders, etc., the processes, systems, and methodsdescribed above can be similarly used to permanently or temporarily fix,attach, align, or establish relation between any two or more parts ofthe same or different items, products, areas, etc., including those notdirectly related to electronics. Examples include in lighting,furniture, automotive, mechanical instruments or machines, electronics,electrical systems and components, batteries, cases, purses, clothing,footwear, or any other number of applications. Other examples can bedeveloped in accordance with other applications.

Some aspects of the present invention can be conveniently implementedusing a conventional general purpose or a specialized digital computer,microprocessor, or electronic circuitry programmed according to theteachings of the present disclosure. Appropriate software coding canreadily be prepared by skilled programmers and circuit designers basedon the teachings of the present disclosure, as will be apparent to thoseskilled in the art.

In some embodiments, the present invention includes a computer programproduct which is a storage medium (media) having instructions storedthereon/in which can be used to program a computer to perform any of theprocesses of the present invention. The storage medium can include, butis not limited to, any type of disk including floppy disks, opticaldiscs, DVD, CD-ROMs, microdrive, and magneto-optical disks, ROMs, RAMs,EPROMs, EEPROMs, DRAMs, VRAMs, flash memory devices, magnetic or opticalcards, nanosystems (including molecular memory ICs), or any type ofmedia or device suitable for storing instructions and/or data.

The foregoing description of the present invention has been provided forthe purposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise forms disclosed.Many modifications and variations will be apparent to the practitionerskilled in the art. The embodiments were chosen and described in orderto best explain the principles of the invention and its practicalapplication, thereby enabling others skilled in the art to understandthe invention for various embodiments and with various modificationsthat are suited to the particular use contemplated. It is intended thatthe scope of the invention be defined by the following claims and theirequivalence.

What is claimed is:
 1. A system for inductive charging with support formultiple charging protocols, comprising: a base unit having one or morecharger coils, for use in inductive charging; one or more componentswithin the base unit and/or a mobile device for supporting multipledifferent charging protocols, for use with the mobile device; andwherein, when a mobile device having one or more receiver coils orreceivers associated with, is placed in proximity to the base unit, thesystem determines a charging protocol for use with the charger coil toinductively generate a current in the receiver coil or receiverassociated with the mobile device, to charge or power the mobile device.2. The system of claim 1, wherein the base unit and mobile devicecommunicate with each other prior to and/or during charging or poweringto determine a protocol to be used to charge or power the mobile device.3. The system of claim 1, wherein the base unit and mobile devicecommunicate with each other through a separate coil, radio frequencylink, or optical communication, to determine a type of base unit andmobile device.
 4. The system of claim 1, wherein the base unit andmobile device communicate with each other to verify the authenticity,power requirements and/or other characteristics of the mobile device ora battery therein and/or verify or handshake the presence of the mobiledevice proximate the base unit.
 5. The system of claim 1, wherein thebase unit and/or mobile device includes a microcontroller that makesappropriate adjustments to achieve a desired output voltage, current orpower, to be used using in charging or powering the mobile device. 6.The system of claim 1, wherein the base unit and/or mobile deviceincludes a microcontroller that receives a communication signal from adetection/demodulation circuit and, depending on an algorithm used,makes appropriate adjustments to the output voltage, current or power ofthe base unit.
 7. The system of claim 1, wherein the base unit and/ormobile device includes a microcontroller that implements in firmware analgorithm for supporting multiple different charging protocols, for usewith the mobile device, and/or measures voltages and currents, flags,and temperatures at appropriate locations for proper operation.
 8. Thesystem of claim 1, wherein, upon detection of a particular event, thebase unit and/or mobile device can perform an action including one ofnotifying a user, or controlling the charging or powering of the mobiledevice or another action.
 9. The system of claim 1, wherein the baseunit and/or mobile device includes a battery charging circuitry andalgorithm for use with different types of batteries and mobile devices,to optimally control the charging or powering of those different typesof batteries and mobile devices.
 10. The system of claim 1, wherein thebase unit is provided within an automobile, for use in charging orpowering one or more mobile devices within the automobile, and/or themobile device is an automobile that can be charged by a base unit.
 11. Amethod of inductive charging with support for multiple chargingprotocols, comprising the steps of: providing a base unit having one ormore charger coils, for use in inductive charging; providing one or morecomponents within the base unit and/or a mobile device for supportingmultiple different charging protocols, for use with the mobile device;and wherein, when a mobile device having one or more receiver coils orreceivers associated with, is placed in proximity to the base unit, thesystem determines a charging protocol for use with the charger coil toinductively generate a current in the receiver coil or receiverassociated with the mobile device, to charge or power the mobile device.12. The method of claim 1, wherein the base unit and mobile devicecommunicate with each other prior to and/or during charging or poweringto determine a protocol to be used to charge or power the mobile device.13. The method of claim 11, wherein the base unit and mobile devicecommunicate with each other through a separate coil, radio frequencylink, or optical communication, to determine a type of base unit andmobile device.
 14. The method of claim 11, wherein the base unit andmobile device communicate with each other to verify the authenticity,power requirements and/or other characteristics of the mobile device ora battery therein and/or verify or handshake the presence of the mobiledevice proximate the base unit.
 15. The method of claim 11, wherein thebase unit and/or mobile device includes a microcontroller that makesappropriate adjustments to achieve a desired output voltage, current orpower, to be used using in charging or powering the mobile device. 16.The method of claim 11, wherein the base unit and/or mobile deviceincludes a microcontroller that receives a communication signal from adetection/demodulation circuit and, depending on an algorithm used,makes appropriate adjustments to the output voltage, current or power ofthe base unit.
 17. The method of claim 11, wherein the base unit and/ormobile device includes a microcontroller that implements in firmware analgorithm for supporting multiple different charging protocols, for usewith the mobile device, and/or measures voltages and currents, flags,and temperatures at appropriate locations for proper operation.
 18. Themethod of claim 11, wherein, upon detection of a particular event, thebase unit and/or mobile device can perform an action including one ofnotifying a user, or controlling the charging or powering of the mobiledevice or another action.
 19. The method of claim 11, wherein the baseunit and/or mobile device includes a battery charging circuitry andalgorithm for use with different types of batteries and mobile devices,to optimally control the charging or powering of those different typesof batteries and mobile devices.
 20. The method of claim 11, wherein thebase unit is provided within an automobile, for use in charging orpowering one or more mobile devices within the automobile, and/or themobile device is an automobile that can be charged by a base unit.